Tertullian of Carthage: Repentance, the Church as Christ

 With one and two individuals, there is the Church; and the Church, indeed, is Christ. Therefore, when you cast yourself at the knees of the brethren, you are dealing with Christ, you are entreating Christ. In the same say, when they shed tears over you, it is Christ who suffers, Christ who implores the Father. When it is a son who asks, the request is always more easily granted. How very grand is the reward of modesty, which the concealing of our sin promises! If in fact we conceal something from the notice of men, shall we at the same time hide it from God? Are, then, the good opinion of men and the knowledge of God to be equated? Is it better to be damned in secret than to be absolved in public? "But it is a miserable thing thus to come to confession!". Yes, evil leads to misery. But where there is repentance misery ceases, because it is thereby turned to salvation.

+Tertullian of Carthage, from Of the Second Baptism, from Ante-Nicene Fathers

St. Maximos the Confessor: To love God is to love every man

 The person who loves God cannot help loving every man as himself, even though he is grieved by the passions of those who are not yet purified. But when they amend their lives, his delight is indescribable and knows no bounds.
+St. Maximos the Confessor, from Four Centuries on Charity, Century 1, #13

Archimandrite Seraphim (Aleksiev): On those who think they have no great sins

 Those who think that they do not have any great sins are actually blind. They must pray to God to enable them to perceive their sins and to save themselves from the extremely fatal spiritual delusion that they do not have any particular sins. Even if their sins are as small as specks of dust, if they are not cleaned with constant Confession, they pile up and dirty the room of the heart so that the high heavenly Guest cannot enter there.

The small sins are often more dangerous than the greatest crimes, because the latter weigh heavily on the conscience and insist on being atoned for, confessed, settled, erased, while the small sins do not weigh too much on the soul, but they have that perilous property of making it insensitive to the grace of God and indifferent to salvation. Fewer people have perished from ferocious wild beasts than have from small microbes, invisible to the naked eye. By being considered insignificant, the small sins are usually passed by without any attention. They are easily forgotten, but they create in man the most terrible habit - the habit of sinning, of dulling his moral consciousness.

+Archimandrite Seraphim (Aleksiev), from The Forgotten Medicine, The Mystery of Repentance, Chapter 4, Objections to Confession

St. Isaac the Syrian: On thankfulness to God

The thanksgiving of the recipient incites the giver to give gifts greater than the first. He that returns no thanks in small matters is a dissembler and dishonest in greater ones also. If a man is ill and recognizes his ailment, his healing will be easy. If he confesses his pain, he draws nigh its cure. The pangs of the unyielding heart will be multiplied, and the patient who resists his physician amplified his torment. There is no unpardonable sin, save the unrepented one. Nor does any gift remain without addition, save that which is received without thanksgiving. The fool's portion is small in his eyes.
+St. Isaac the Syrian, from The Ascetical Homilies, Homily 2 On thankfulness to God, in which there are also essential elementary lessons.